ES2702554T3 - Plant and air drying method of chopped food - Google Patents

Abstract

Air dried food drying plant, including - a food conveyor (10) chopped (1) defining a transport surface (11) and a transport direction - a plurality of blow ducts (20) including blowing openings (21) that channel a flow of air treated with a temperature between 4 ° C and 60 ° C and a controlled humidity; characterized in that: - the conveyor includes air treatment sections (12) whose transport surfaces (11) are facing and adjacent to said blowing openings (21) of at least one of said plurality of blow ducts (20), said flow of treated air being directed to a treatment speed against said transport surface (11) of the air treatment sections (12), directly affecting the chopped food (1) in a downward or upward direction through the conveyor, being this openwork; - the conveyor (10) also includes rest sections (13) interposed between said air treatment sections (12), whose transport surface (11) is not facing blowing openings (21), nor is it subject to a flow of air directed against said transport surface (11), and said drying plant comprising a plurality of said rest sections (13) interleaved between a plurality of air treatment sections (12) along the direction of transport .

Description

DESCRIPTION

Plant and air drying method of chopped food

Field of technique

The present invention concerns a plant and an air drying method of chopped food, of the type in which the chopped food is placed spread on a conveyor leading the chopped food and exposes it to a temperature treated air flow and / or humidity determined and advantageously controlled, producing an accelerated dehydration of the chopped food for its curing or drying.

State of the art

The treatment of food drying by treated air flow is widely known, for example by WO03073871A1 and EP2213178A1, which describe the curing of food by a treated air flow, however in this background the use of feed conduits is not described. blown facing a conveyor, producing an air flow approximately perpendicular to said conveyor.

It is also known, for example, US4726766 and US4544352, the use of treatment plants equipped with a spiral conveyor provided with superimposed sections, with a plurality of blow ducts interposed between said superposed sections of the conveyor, thus allowing to apply a flow of air treated on each of said overlapping sections and the food deposited therein.

However, these last two known documents describe ovens for cooking food, and not for drying. In these documents the blowing ducts cover only some sections of the conveyor, thus leaving other sections of the conveyor lacking a treated air flow, but the whole conveyor being contained in a housing that encloses a volume of air inside it that is heated to cooking temperatures, so that all the air contained in said casing will have said cooking temperature and an identical relative humidity, thus producing a homogeneous cooking both in the sections subjected to the air flow and in the sections lacking said treated air flow. Thus these documents do not describe a food treatment with a treated air flow and sections not treated with air successively, because in the sections lacking air flow, the surrounding air will be at cooking temperature and therefore also produce the cooking of the food in said sections.

The drying by means of a flow of treated air has, in pieces of a certain thickness, the problem of producing a dehydration of the bark of the treated pieces superior to the dehydration of its core. This problem is described in documents US4890394 and US2408434, although not applied to food but to constructive elements such as wood and plaster, but in these documents propose to solve this problem by external drying by treated air flow and internal drying by microwave or other radiofrequency forms. BRIEF DESCRIPTION OF THE INVENTION

The present invention concerns, according to a first aspect of the present invention, an air dried food-drying plant.

Said drying plant produces the drying by dehydration of chopped food by applying a flow of air treated on said chopped food. It will be understood that the chopped food refers to pieces of edible products. Preferably said pieces will have a thickness greater than 0.5 mm and less than 30 or 40 mm, regardless of whether they are composed of a single piece of food, or of an agglomerate, mash, porridge or food aggregate.

So the proposed plant includes:

• a chopped food conveyor that defines a transport surface and a transport direction; • a plurality of blowing ducts including blowing openings that channel a flow of treated air at a treatment rate with a controlled temperature between 4 ° C and 60 ° C and a controlled humidity.

Said conveyor consists of an automatically driven mechanism that moves the chopped food deposited on a transport surface in a certain direction here called transport direction. Examples of said conveyors can be, by way of non-limiting example, a conveyor belt, a conveyor grid, a tray conveyor (the pallets being the transport surface), a vibrating table, a guided carriage, etc. The actuation of said conveyor will take place, also by way of example, by the action of an electric or hydraulic motor controlled by a programmable control unit, which could receive signals from different sensors, such as temperature and humidity sensors.

The air treated will be air to which the temperature and / or humidity have been modified by means of air treatment devices, such as heating machines, chillers, heat exchangers, dehumidifiers, etc., and which is expected to be driven through of said blowing ducts by means of air impellers, for example pumps or fans, which give said speed of treatment.

The proposed plant also includes, in a novel way, the following characteristics:

• the conveyor includes air handling sections whose transport surfaces are facing and adjacent to said blowing openings of at least one of said plurality of blowpipes, said treated air flow being channeled against said transport surface of the sections of air treatment in a downward or upward direction;

• the conveyor also includes rest sections interposed between said air treatment sections, whose transport surface is not facing blowing openings, nor is it subjected to an air flow, and comprising a plurality of rest sections interspersed between sections of treatment by air along the direction of transport.

It will be understood that the sections of air treatment and those of rest are interspersed in the transport direction, allowing the conveyor to transfer the chopped foods from a section of treatment by air to a stretch of rest and again to a section of air treatment. , and so on until reaching the exit at the end of the conveyor at the exit of the drying plant.

As the treated air flow projected against the transport surface in an upward or downward direction from blowing openings adjacent to and facing said transport surface, all the chopped food disposed on said transport surface will receive a direct input of treated air, without the treated air received by a piece of chopped food having previously passed through other pieces of chopped food, which would alter the speed, humidity and temperature of the treated air, therefore the drying of all pieces of chopped food will be uniform.

According to an optional embodiment, the treated air will have a relative humidity lower than 35%, or preferably comprised between 5% and 25%, and / or a temperature between 30 ° and 50 °. It is further contemplated that the aforementioned treatment speed will be greater than 1 m / s, or preferably greater than 1.5 m / s.

It is also contemplated that the air surrounding the rest sections has a relative humidity higher than the relative humidity of the treated air, since the surrounding air will be at least partially air previously expelled through the blow openings that will have absorbed moisture from the food chopped It is also considered that the surrounding air will have a temperature lower than the temperature of the treated air, the temperature of the treated air being higher than that of the chopped food fed to the drying plant, or a temperature higher than the temperature of the treated air, being the temperature of the treated air lower than that of the food cut into the drying plant. This means that the treated air, after coming into contact with the chopped food, its temperature will be modified as a result of the temperature difference between said treated air and said chopped food, and as a result of the evaporation process, which produces a reduction in the temperature of both chopped food and air. As a result of this process, the air surrounding the rest sections, which at least partly will be air previously expelled through the blow openings, will have a temperature different from the temperature of the treated air.

In a preferred embodiment of the proposed invention, the conveyor is a conveyor with superimposed levels or a spiral conveyor with superimposed levels, said conveyor being able to be perforated or not. That is to say that the conveyor can consist of different levels arranged one above the other and independent of each other, for example parallel levels each fed independently with chopped food, or a same conveyor whose length has been wound in a spiral with overlapping levels, so that the chopped food fed to said conveyor travels all levels thereof during its transportation in the direction of transport.

There are many conveyors of this type on the market and are widely used in the industry and known to those skilled in the art, for example composite sliding skins or meshes dragged by chains or driven from their sides, or conveyor belts, roller tables on which to slide trays, etc.

It is also proposed that said plurality of blow ducts be arranged interspersed between said superposed levels of the conveyor or spiral conveyor, so that conveyor levels with levels of blow ducts will be interleaved between said conveyor levels. According to a preferred embodiment, said conveyor includes straight conveyor sections arranged in superposed levels, and where said blowing conduits include straight blowing conduits superimposed on said straight conveyor sections, said straight conveyor sections constituting the air treatment sections. This realization lowers the manufacturing costs of the proposed plant, since the sections of air treatment, whose transport surface is facing said blow openings, are straight which allows the blow ducts are also straight and therefore more economic

Additionally, it is proposed that said conveyor includes superimposed curved conveyor sections without blowing ducts provided with blowing openings interposed between said superposed curved conveyor sections, said curved conveyor sections forming the rest sections. The curved areas of the conveyor are reserved to place the resting areas in them, thus avoiding the placement of blowing ducts, with their corresponding blowing openings, in said curved sections, which would make the plant more expensive. It is optionally contemplated that the air treatment sections and the rest sections are located in different enclosures at least partially delimited by air-impermeable dividing elements, to allow the air surrounding both sections to have some differentiated temperature and / or humidity characteristics. . With regard to the blowing ducts, it is proposed that the face provided with blow openings of at least one blowing duct be parallel to the transport surface of the conveyor section to which it is facing, said blow duct being elongated in a direction parallel to the transport direction of the conveyor section to which it is facing. Thus, according to said configuration, at least one of the blowing ducts is a conduit that runs in the direction of transport and with a face parallel to the transport surface, thus allowing to have blow openings homogeneously distributed on the transport surface. during a long section thereof, which preferably corresponds to a section of air treatment.

Preferably at least one section of blowing duct has a constant width and a decreasing variable section in the direction of air circulation through its interior. The constant width of the blowing duct allows to have a face with a constant surface on which to place the blowing openings, and the decreasing variable section, which is achieved by reducing the height of the duct, allows to maintain a constant air flow in all its length in spite of the air outlet through the blow openings, and the loss of load of the transported air. In this way it is achieved that all the blow openings provide an equal air flow.

It is also proposed that, according to a preferred embodiment, each of said air treatment sections and / or each of said rest sections have a length, in the direction of transport, of at least five meters, thus achieving a time of treatment of the chopped food transported enough for proper drying to occur, considering an adjustable transport speed within the usual range of operation of this type of conveyors in the industry.

Furthermore, or alternatively, it is proposed that the length of the at least one rest section be between 40% and 60% of the length of the preceding air treatment sections, in the transport direction.

It is also proposed that suction ducts be arranged adjacent to the air treatment sections, the air being absorbed by said suction ducts used to obtain said treated air. Thus said suction ducts will be communicated with said air treatment devices that produce and provide treated air, allowing the recirculation of all or part of the suctioned air to reuse it as treated air, and / or to recover thermal energy from said air. air suctioned to modify the temperature of the treated air by means of a heat exchanger equipment.

According to another embodiment, at least part of said suction ducts are located in the limits between the air treatment sections and the rest sections.

According to a second aspect of the invention, this refers to a method of drying food chopped by air, said method being applied by a plant that includes:

• a chopped food conveyor that defines a transport surface and a transport direction; • a plurality of blowing ducts including blowing openings that channel a flow of treated air at a treatment rate with a controlled temperature comprised between 4 ° C and 60 ° C and a controlled humidity;

and the method comprising the following steps:

a) feeding said conveying surface of the conveyor with chopped food;

b) transporting, by actuating said conveyor, said chopped food to an air treatment section facing said blowing openings, said chopped food being confronted with said blowing openings of said blowing conduits;

c) subjecting said chopped food to a drying treatment by means of a flow of said treated air during a drying time, producing a reduction of the moisture of the crust of said chopped food;

d) transporting, by means of the actuation of said conveyor, said chopped food to a rest section of the conveyor, said chopped food being exposed to a surrounding air composed at least in part by untreated environmental air and lacking an air flow, producing a rehydration of the crust of the food cut with the internal humidity of the chopped food, tending to reach a homogeneous humidity in all the chopped food;

e) repeating the steps b), c) and d) cyclically, along a succession of stretches of air treatment and interspersed rest, until reaching a certain drying of the chopped food.

Thus the chopped food is exposed to a flow of treated air along the air treatment sections of the conveyor, coming from blowing openings facing the transport surface of the conveyor, producing dehydration of the outer crust of the food chopped Subsequently said chopped food is transported to the resting sections, where said chopped food is not exposed to an air flow, and where the surrounding air is at least partially untreated environmental air, so that the dehydration of the bark of the bark is stopped. chopped food, and the moisture of each piece of chopped food tends to distribute evenly throughout the piece of food cut, migrating from the core to the partially dehydrated crust, thus reducing the moisture of said core. Said process of external drying by air flow and internal drying by migration of the internal moisture to the bark can be repeated cyclically alternating stretches of treatment by air with stretches of rest, until reaching the degree of dehydration desired. Said predetermined drying will be established, for example, depending on the moisture loss or the desired weight of the chopped food, which may be weight loss values of, for example, between 22% and 70% with respect to the weight prior to treatment. Preferably the objective to be achieved will be a chopped food whose water activity prevents the growth of pathogenic microorganisms, allowing to conserve the product at room temperature. Said water activity will preferably be less than 0.85.

Preferably the conveyor displaces the chopped food at a constant and uniform speed, and the length ratio between a rest section and the immediately preceding air treatment section will be between 40% and 60%, thus achieving treatment times by air similar to resting times.

It will be understood that references to geometric position, such as parallel, perpendicular, tangent, etc. they admit deviations of up to ± 5 ° with respect to the theoretical position defined by said nomenclature. It will also be considered that those characteristics described as parts of the treatment plant are applicable to the method and vice versa.

Through the proposed drying plant and drying method, which represent an evolution and improvement of the air drying systems known to date, a quick drying of sliced or sliced cured sausage based on the improvement of time efficiency is achieved drying and in the improvement of the energy consumption necessary to achieve the desired degree of drying.

The process begins, in an example of embodiment, with the manufacture of bars of meat product. Then, depending on the type of dry chopped food to be obtained, known in the sector as a meat snack, you can perform different pre-treatments such as fermentation, cooking or simply start the drying process. In the case of having carried out some process prior to drying, and whenever necessary for its stabilization or for the improvement of the subsequent cut, it is possible to freeze the product. Finally, it can be cut to give it the desired shape and size and start drying through the drying plant and the drying process described above, where, once finished, meat snacks ready to be packaged will be obtained.

It is a continuous and automated process that, between pre-treatment of the product, freezing and drying treatment, allows the generation of new products and formats of snacks to be accelerated exponentially. The freezing prior to drying allows the process to be highly versatile and functional, not only because it can have stock stored to be transformed into a final product when required, but also allows the product to be brought to the limit during the previous phases and stabilize it like this later. In the case of fermentation, for example, it makes it possible to work at extreme temperatures and relative humidity, unthinkable in traditional methods, because once the desired pH and level of cure have been reached, the product is frozen, stopping any process or evolution that may suffer.

The range of temperatures and humidity at which the equipment works has allowed the creation of differential products with high added value which, due to their physicochemical and organoleptic characteristics, require these drying conditions.

The fact of being able to use different temperatures and humidity in the process itself and the ease of being able to pass from one to another by adjusting and setting the drying plant, make the process very versatile when it comes to producing different products, allowing to develop and produce new and innovative stable meat snacks at room temperature, customized in texture, flavor and aroma for each type of consumer.

The proposed plant and method is expected to be used, according to a possible implementation, to obtain three basic types of meat snacks:

• Dry meat cut into cubes or strips

• Extruded meat crushing

• Crunchy meat slices

In the case of dried meat cut into cubes or strips, it should be noted that this process to date is little automated in the industry and that, although some large producers now manufacture more industrially by injecting the curing solution into the dough with a back massage on the drum, the drying process requires the manual placement of the meat strips in carts, either in trays or bars. This involves a large amount of labor and product development in lots small enough to be handled manually. The proposed plant and process allow these manual processes to be replaced by automated processes, obtaining equivalent results at a lower cost.

According to an example of embodiment, part of a base of lean meat material, stabilized, pasteurized and subsequently frozen and to which, in the moment prior to drying is given the desired shape. Different flavors and / or spices may be applied depending on the variety to be packaged, for example by adding spices and / or artificial flavors or flavors to said lean meat material, for example by giving it a spicy flavor, or teriyaki sauce flavor , cheese flavor, etc., and proceed to its drying continuously and automatically.

This new concept allows the possibility of starting from a single generic raw material and, later modifying the specifications of cutting, addition of additives, and drying of the chopped food, differentiating the final product simply by adjusting the operating parameters of the installation. This represents a great advantage in logistics and planning, since it allows starting from the same base and producing the product on demand continuously and automatically. This flexibility that allows the proposed plant and method is also basic for any line of snacks that must adjust to the constant changes in market preferences. As for the extruded meat shreds, this is the evolution of traditional bar sausages, but with final calibers between 3 and 15 mm and stable at room temperature.

Generally, for the production of these extruded meat snacks the stuffing is used by co-extrusion with alginate or collagen solution of the meat paste initially prepared. Once stuffed, we proceed to the fermentation, drying and, finally, weighing and packaging of the finished product, being the traditional drying process again very slow (about three days) and inefficient. .

Once again, the implementation of the drying plant and the proposed drying method allow this process to be accelerated and cheaper, as with the case of cut dry meat products.

In addition, the drying plant and the proposed method allow not to use stuffing casing since, using the accelerated drying process, a layer of dry protein is immediately formed around the product that helps maintain the shape and consistency of the same.

As for the crunchy meat slices, they consist of meat product cut into thin slices that are dried until they reach a crispy texture without requiring frying.

In the process prior to drying, the organoleptic characteristics that will confer the desired texture on the final chip are developed. This system allows to apply both fermentation and cooking before drying. This previous step is especially important for the development of the texture in the cured chips without cooking, since the previous cooking with selected strains of Micrococos will generate the necessary proteolysis so that the chip, once in the mouth and rehydrated during chewing, does not recover the gummy texture typical of dried meat. This previous process will be for example, the one described in the patent application EP2912957, of the inventors themselves, which has complementary characteristics and offers synergies with the invention proposed in this document.

The fermented chips are dried to a completely crunchy texture using treatment temperatures below the coagulation temperature of the myofibrillar proteins, thus avoiding any change in the texture of the cured product during chewing, but also the loss of the volatile aromas generated during the fermentation. To get the crispy, slicing is done to a thickness less than a millimeter and the proposed drying allows a more traditional look, which allows to make chips of cured ham or chorizo, chicken, turkey, with and without smoked, etc. As in the production of classic snacks you can aromatize or add spices online and automatically, to generate more references from the same base.

The crispy meat sliced products will preferably have a humidity of less than 6% and a water activity of less than 0.4, and will require an early packing in an airtight container to avoid rehydration and therefore the loss of its crunchy quality.

Other characteristics of the invention will appear in the following detailed description of an exemplary embodiment. Brief description of the figures

The foregoing and other advantages and features will be more fully understood from the following detailed description of an exemplary embodiment with reference to the accompanying drawings, which should be taken by way of illustration and not limitation, in which:

Fig. 1 shows a schematic perspective view of a chopped food drying plant equipped with a spiral conveyor with sixteen superposed levels each endowed with two straight sections and two extreme curved sections, and including blow ducts interspersed between the straight sections of said superposed levels and suction ducts disposed adjacent to said conveyor;

Fig. 2 shows a schematic plan view of the conveyor shown in Fig. 1, stripped of the blow and suction ducts;

Fig. 3 shows an enlarged cross-section of a plurality of superposed levels of the conveyor, corresponding to a section of the corresponding air treatment sections, where blowing ducts interposed between the levels of the conveyor provide a flow of treated air in a descending direction on each of the air treatment sections through blowing openings provided in said blowing ducts;

Fig. 4 shows an enlarged cross section of a plurality of levels of the superimposed conveyor, corresponding to a section of the corresponding rest sections, where the chopped food is not subjected to any treated or untreated air flow, allowing rehydration of the crust of the chopped food by means of the migration of the interior humidity of said chopped food.

Detailed description of an embodiment

Fig. 1 shows, according to an embodiment of the present invention with illustrative non-limiting character, a chopped food drying plant 1 consisting of a conveyor 10 in the form of a spiral conveyor with superimposed levels, each level comprising a first section straight, connected at one end to a first curved section, connected in continuity to a second straight section, and connected in turn to a second curved section.

Each of said sections is slightly sloped, so that upon completion of a complete turn, the end end of the conveyor 10 of one level is above the initial end of said level, and coincident with the initial end of the next level, in the transportation address Connecting a plurality of levels by their initial and final ends is obtained said spiral conveyor 10 with superposed levels, which has a great length and occupies a scarce volume.

Optionally a plurality of spiral conveyors 10 with superposed levels can be connected so that the chopped food 1 passes through said plurality of spiral conveyors 10 before completing its treatment.

The aforementioned conveyor 10 may consist of conveyor belts defining a transport surface, or sliding or trailing mechanisms for trays, which define said transport surfaces on which the chopped food 1 which is fed to the plant is deposited. air drying described.

The above-described straight sections of the conveyor 10 have an approximate length of between 8 and 12 meters, and have their respective transport surfaces 11 facing blowing openings 21 provided in blowing ducts 20 interspersed between the superposed levels of the conveyor 10, so that said straight sections define sections of air treatment 12 of the chopped food 1, when this is exposed to an upward or downward flow of treated air driven through said blowing openings 21. In the present embodiment, the blow ducts 20 interposed between the straight sections of the conveyor 10 are straight conduits that extend in a direction parallel to the conveying direction of the conveyor 10, as can be seen in Fig. 3.

The blowing ducts 20 are connected to air treatment devices, not shown in Fig. 1, such as for example heating machines, chillers, heat exchangers, dehumidifiers, etc., which allow to provide and push through said blow ducts. 20 a controlled flow of treated air whose temperature and humidity are controlled, the controlled temperature being between 4 ° C and 60 ° C and a controlled humidity, although preferably the temperature will be between 30 ° and 50 ° C, and the humidity of less than 30%, for example between 5% and 25%.

In the embodiment shown, four initial blowing ducts 20 not interleaved between levels of the conveyor are each divided into eight blow ducts 20 interspersed between superimposed levels of the conveyor 10, providing a total of thirty two air treatment sections 12, each facing a blowing duct 20, corresponding to sixteen superposed levels.

On the contrary, the transport surface 11 of the above-described curved sections of the conveyor, which will also have an approximate length of between 8 and 12 meters measured on its axis, is not confronted with blow openings 21, so in said sections the chopped food 1 transported is not subjected to a flow of treated air, the air surrounding said curved air sections being with a humidity higher than the humidity of the treated air, and preferably having a temperature different from the temperature of the treated air, defining said sections curved portions of rest 13 of the chopped food 1, shown in section in Fig. 4.

For example, if the temperature of the treated air is between 30 ° C and 60 ° C, and the temperature of the chopped food is lower than the aforementioned 30 ° C, the temperature of the air surrounding the rest sections will be lower than the temperature of the treated air. Likewise, if the temperature of the treated air is for example between 4 ° C and 15 ° C, and the temperature of the chopped food is higher than the temperature of the air treated in for example 5 ° C, then the temperature of the surrounding air will be higher than the treated air temperature.

Thus, said conveyor 10 alternates air treatment sections 12 with rest sections 13, corresponding respectively to straight and curved sections of the conveyor.

This described construction is simple, by not requiring more complex curved blowing ducts, facing the curved sections of the conveyor.

In the air treatment sections 12 the flow of treated air impinges on the chopped food 1 transported deposited on the transport surface 11 in a uniform manner, so that said flow of treated air dries the outer crust of said chopped food 1, tearing off and dragging its surface moisture through said air flow. Once a certain degree of drying of said bark has been reached, it prevents the flow of treated air from producing a correct drying of the inner core of the chopped food 1, since the already dry bark can not continue drying any more, and its thickness prevents the flow of treated air produces the drying of the kernel of the chopped food 1.

To avoid this phenomenon, it is proposed to have rest sections 13 interposed between the air treatment sections 12. In said rest sections 13 there is no flow of treated air incident on the chopped food 1, and therefore there is no additional drying of the bark in said resting sections 13. On the other hand, the moisture contained inside the chopped food 1 tends to be distributed homogeneously, so that in the resting sections 13 said moisture has time to migrate from the core towards the previously dried bark, thus producing a drying of the core reducing its moisture content and rehydrating the bark from the inside.

After this stage, the chopped food 1 is again conducted to an air treatment section 12 where the flow of treated air drains the crust of the chopped food 1 again.

This procedure can be repeated as many times as necessary until reaching a degree of drying of the optimum chopped food set 1.

Beside the air treatment sections 12 there are suction ducts 22 which suck in the surrounding air which, for the most part, will be pre-treated air driven through the blow openings 21 and which will have absorbed part of the moisture from the air. treated food 1.

Preferably said suction ducts 22 will be connected to the air treatment devices that provide the treated air, so that part or all of the air sucked through the suction ducts 22 can be reused as treated air, and / or part of the energy contained in said suctioned air can be recovered, for example by means of heat exchangers.

A method is also proposed which consists in alternating the treatment of the chopped food 1 by a treated air flow applied in air treatment sections 12 of a conveyor 10, and by transporting the chopped food 1 in rest sections 13 where there is no air flow, repeating these stages cyclically until reaching the desired degree of drying of the chopped food. Preferably the transport speed of the chopped food will be constant.

Claims (15)

1. - Air dried food drying plant, which includes • a conveyor (10) of chopped food (1) defining a transport surface (11) and a transport direction • a plurality of blowing ducts (20) including blowing openings (21) that channel a flow of treated air with a temperature comprised between 4 ° C and 60 ° C and a controlled humidity; characterized because: • the conveyor includes air handling sections (12) whose conveying surfaces (11) face and adjacent to said blowing openings (21) of at least one of said plurality of blow ducts (20), said flow being of treated air directed to a treatment speed against said transport surface (11) of the air treatment sections (12), directly affecting the chopped food (1) in a downward or upward direction through the conveyor, this being drawn ; • the conveyor (10) also includes rest sections (13) interposed between said air treatment sections (12), whose transport surface (11) is not facing blowing openings (21), nor is it subjected to a flow of air directed against said transport surface (11), and said drying plant comprising a plurality of said rest sections (13) interleaved between a plurality of air treatment sections (12) along the transport direction. 2. - Drying plant according to claim 1, wherein the characteristics of the treated air are selected from: • a relative humidity less than 35% or between 5% and 25%; • a temperature between 30 ° and 50 °; • a treated air treatment speed greater than 1 m / s or greater than 1.5 m / s. 3. - Drying plant according to claim 1, wherein the characteristics of the air surrounding the rest sections (13) are selected from: • a relative humidity higher than the relative humidity of the treated air; • a temperature below the temperature of the treated air, the temperature of the treated air being higher than that of the chopped food fed to the drying plant, or a temperature above the temperature of the treated air, the temperature of the treated air being lower than the temperature of the chopped food to the drying plant. 4. - Drying plant according to claim 1, 2 or 3, wherein the conveyor (10) is selected from: • a conveyor with superimposed levels; • an openwork conveyor with superimposed levels; • a spiral conveyor with superimposed levels; • an openwork spiral conveyor with superimposed levels. 5. - Drying plant according to claim 4, wherein said plurality of blow ducts (20) are arranged interspersed between said superposed levels of the conveyor (10) or the spiral conveyor. 6. - Drying plant according to claim 5, wherein said conveyor includes straight conveyor sections arranged in superposed levels, and wherein said blowing ducts (20) include straight blowing ducts superimposed on said straight conveyor sections, forming said sections of Straight conveyor the air treatment sections (12). 7. - Drying plant according to claim 5 or 6, wherein said conveyor (10) includes curved conveyor sections superimposed, and where said curved conveyor sections lack blowing ducts (20) provided with blow openings (21) interleaved between said curved conveyor sections superimposed, said curved conveyor sections forming the rest sections (13). 8. - Drying plant according to any one of the preceding claims, wherein the face provided with blow openings (21) of at least one blow pipe (20) is parallel to the transport surface (11) of the conveyor section to the which is facing, said blow pipe (20) being elongated in a direction parallel to the transport direction of the conveyor section (10) to which it is facing. 9. - Drying plant according to any one of the preceding claims, wherein at least one section of blow pipe (10) has a constant width and a decreasing variable section in the direction of air circulation through its interior. 10. - Drying plant according to any one of the preceding claims, wherein the characteristics of the conveyor are selected from the following: • each of said air treatment sections (12) has a length, in the direction of transport, greater than five meters; • each of said rest sections (13) has a length, in the direction of transport, greater than five meters; • the length of at least one rest section (13) is between 40% and 60% of the length of the preceding air treatment sections (12), in the transport direction. 11. - Drying plant according to any one of the preceding claims, wherein suction ducts (22) are arranged adjacent to the air treatment sections (12), the air being absorbed by said suction ducts (22) used for Obtaining said treated air. 12. - Drying plant according to claim 11, wherein at least part of said suction ducts (22) are located in the boundaries between the air treatment sections (12) and the rest sections (13). 13. - Air drying method of chopped food, said method being applied by a plant that includes: • a transporter (10) of chopped food (1) defining a transport surface (11) and a transport direction; • a plurality of blowing ducts (20) including blowing openings (21) that channel a flow of treated air with a temperature comprised between 4 ° C and 60 ° C and a controlled humidity; the method being characterized in that it comprises the following steps: a) feeding said transport surface (11) of the conveyor (10) with chopped food (1); b) conveying, by means of the operation of said conveyor (10), said chopped food (1) to an air treatment section (12) facing said blow openings (21), said chopped food (1) being left facing said blowing openings (21) of said blowing ducts (20); c) subjecting said chopped food (1) to a drying treatment by means of a flow of said treated air directed at a treatment speed against said transport surface (11) of the air treatment sections (12), directly affecting the food chopped (1) during a drying time, producing a reduction of the moisture of the crust of said chopped food (1); d) transport, by actuating said conveyor (10), said chopped food (1) to a rest section of the conveyor (10), said chopped food (1) being exposed to a surrounding air lacking a directed air flow against said transport surface, during a time of rest, producing a rehydration of the crust of the food chopped with the internal humidity of the chopped food, tending to reach a homogeneous humidity in all the chopped food; e) repeating steps b), c) and d) cyclically, along a succession of a plurality of sections of air treatment (12) and of rest (13) interspersed, until reaching a certain drying of the chopped food (1 ). 14. - Method according to claim 13, wherein the conveyor moves the chopped food (1) at a constant and uniform speed. 15. - Method according to claims 13 or 14, wherein the ratio between drying time and resting time is between 40% and 60%.